A variety of coupling devices which provide the advantages of quick disconnection are disclosed in the prior art. NASA Tech Brief MFF-21007 discloses a two-piece coupling with a positive locking mechanism intended for use in connection with a soil penetrometer for lunar landing modules and for other applications involving the transmission of axial forces. In the NASA mechanism, a spring wire latch fits into a notch to secure the ends of the coupling against axial separation. Disengagement is achieved by first rotating the parts to release the spring from the notch in which it is received.
While such coupling has the advantages of simplicity in construction and operation, it is unsuitable for use in those applications where the parts must be capable of withstanding twisting forces in use. Couplings which resist release when exposed to rotational forces as well as axial forces tend to be relatively complex, expensive, and bulky. Furthermore, constructions which are designed to prevent inadvertent separation when exposed to rotational as well as axial forces also tend to be difficult to manipulate when intentional disconnection is desired.
Endoscopic instruments used in urological procedures and other medical procedures commonly consist of two main elements: an endoscope (or telescope) and the operating instrument itself. Ease of disassembly of such components is important for purposes of cleaning and repair and to permit utilization of the endoscope (a relatively expensive component) with any of a number of different instruments. On the other hand, it is at least equally important that the parts be latched together so that they are not likely to become inadvertently disengaged during a medical procedure. Prior constructions have not been entirely successful in resisting unintentional separation while achieving ease of intentional disconnection, much less by means which are relatively simple, compact, durable, and reliable in operation.
This invention is concerned with a latching mechanism which overcomes the defects and disadvantages of the prior art. Specifically, the latching mechanism of this invention results in an endoscope-instrument assembly in which twisting forces and other forces commonly encountered in the use of the assembly will not result in disconnection or disorientation of the parts, but one in which disconnection may be easily and quickly accomplished when intentional disassembly is desired. It is also a further object of this invention to provide an endoscope latching mechanism which requires a two-step procedure for unlatching the parts but only a single step procedure for coupling them together.
In brief, the latching mechanism involves a pair of telescoping parts, one of the parts being a generally cylindrical body portion of the endoscope and the other part being a socket-providing tube of the instrument. As used herein, the term "instrument" is intended to refer to any of the instruments commonly associated with an endoscope such as, for example, a urological grasping forceps, a so-called working element, a deflecting bridge as used in urology, etc. Reference may be had to co-pending co-owned applications Ser. Nos. 824,839, filed Aug. 15, 1977, and 838,939, filed Oct. 3, 1977, as illustrations of instruments with which the latching mechanism of this invention may be used.
The socket-providing tube of the instrument has at least one lateral opening into which a section of an externally-mounted spring projects. The body portion of the endoscope disposed within the socket includes a first recess which receives that section of the spring when the two parts are fully connected. In addition, the body portion of the endoscope has a second recess which is spaced axially from the first and which receives the inwardly-protruding section of the spring when the parts are in what may be referred to as a partially latched condition. Means in the form of a lug and a lug-receiving recess serve to lock the endoscope and instrument against relative rotation when the parts are fully latched; hence, the only possible relative movement between the parts when they are fully latched is limited axial movement of the endoscope body into its partially latched position. Further axial separation of the parts is prevented by the section of the spring received in the second recess but if, following such limited axial displacement, the endoscope body is rotated relative to the instrument then the spring section will be cammed out of the second recess to release the endoscope for axial removal from the instrument. Although rotation in the second latching stage (i.e., the partially latched condition) is required for disassembly, no rotation is necessary when reassembly of the components takes place; the endoscope is simply inserted axially into the instrument until the body portion is fully received in its socket.
Other structural features, advantages, and objects of the invention will become apparent from the specification and drawings.